When we talk about the Universe, we usually think of a few things: planets, moons, black holes. Yet, one thing stands out, so central to our understanding of space. Stars! Stars are massive balls of plasma found throughout much of outer space. As we’ll see, they are incredibly important to the structure of the Universe. They’re also intensely interesting (and hot)!

What are Stars Made of?

The thing that makes up stars is truly out of this world. It’s called plasma, and we rarely find it on earth. Plasma is a clump of atoms whose electrons have been taken from them. This makes it kind of like a gas. In fact, you’ll probably hear people say that the Sun is made out of gas. Yet only the outer parts of a star contain any.

What else is made of plasma, for reference? On Earth, we find it naturally in lightning. Otherwise, it’s mostly found in man-made things. The simplest are neon signs. These signs energize electrons on neon atoms, pulling them away to form plasma!

Neon Sign

A neon sign. It’s kind of like a very, very tiny star.

You might ask: Why is plasma so rare? In reality, it’s not. Plasma is the most common state of matter in the universe. But, it only exists in extreme heat. That’s something that stars can easily provide, but which is quite rare on Earth.

How do Stars Form?

Our discussion of plasma raises another question. How do these high energy fireballs (stars) get there in the first place? Well, star formation is quite a complicated subject. We can’t go over it all in this article, but you can read more about it here. That said, here are the basics.

Stars need some sort of material to form. This comes from what are called nebulae, or dense clouds of gas in space. Sometimes, gas in these nebulae clumps up. This creates a point with high gravity, kind of like how a dense planet has strong gravity.

The newly formed center of gravity will start to attract all of the gas particles around it. This happens faster and faster until we have what’s called a ‘collapse.’ All at once, lots of things get sucked inwards!

An image of a galaxy.

Huge nebulae may collapse into a small point, like a crinkled piece of foil.

Boom! Most of the matter flies back outwards. Yet some of it remains clumped together tightly, forming a protostar. Around the protostar, nebular matter forms a disk. The stuff in the disk will keep trying to collapse over and over again.

The protostar will push back, but every time it grows a little. Many collapses later, our star becomes really dense and heavy. At this point, it can begin doing fusion, and we consider it a ‘real’ star.

How Many Stars are There?

When you look up into the night sky, how many stars can you see? 100, 500, perhaps even 1000? No matter how many you might find, it’s only a tiny fraction of how many there are in the Universe. To be clear, scientists aren’t totally sure about the exact number. But, their best guess is…let’s give this number some space:

700,000,000,000,000,000,000,000 Stars!

Given how huge stars are, that’s an unbelievable figure! Our sun is only a small star, and one of many, many others. Lucky for us, there’s always a lot to look for up in space.

Why Do Stars Twinkle?

Twinkle, twinkle little star…Oh, we’re still learning!? Shux. Well, on that subject, let’s talk about why stars twinkle. Or rather, what makes them look like they do.

Star designs on black background.

That’s to say, stars don’t really twinkle. The thing we call ‘twinkling’ is actually an effect of our atmosphere. Air in the sky is actually made up of winds blowing in many different directions. Their interaction creates what is called ‘turbulence.’ This is when the air gets rough. You might’ve felt it if you’ve ever been on a plane.

In essence, turbulence is responsible for ‘twinkling.’ As the light from stars passes through rough air, it gets distorted. The distortion depends upon how turbulent the wind is. Differences in distortion are what make stars look like they’re twinkling. Light waves come to us constantly, but they’re almost always changed in some way by our atmosphere.

Other Great Resources:

The University of Oregon on Star Formation:

‘Fun Facts about Stars’ by Ducksters:

Even More on Star Formation:

What are Stars?:

Constellations: Connect the Dots in the Sky:

Written by: Noah Louis-Ferdinand.